1. Technical Field
The present disclosure relates to a Rankine cycle device.
2. Description of the Related Art
Conventionally, Rankine cycle devices are known as devices to carry out power generation. As an example of such Rankine cycle device, there is a known configuration where a working fluid is expanded by a displacement expander to recover power. As illustrated in FIG. 13, Japanese Unexamined Patent Application Publication No. 2002-155707 discloses a Rankine cycle device 600 having an evaporator 603, an expander 604, a condenser 605, and a supply pump 606. The evaporator 603 generates a vapor at high temperatures and high pressures using waste heat of an internal combustion engine 601 as a heat source.
In the Rankine cycle device 600, a pressure Pevp and a temperature Tevp of the vapor supplied to the expander 604 are adjusted to satisfy predetermined relationship. The pressure Pevp of the vapor is adjusted by controlling a number of rotation of the expander 604, and the temperature Tevp of the vapor is adjusted by controlling the amount of water supplied to the evaporator 603. At this time, a ratio of expansion of the expander 604 is set at a predetermined ratio of expansion (set ratio ε of expansion), thereby matching a pressure Pexp2 and a temperature Texp2 of the vapor discharged from the expander 604 to a rated value. As a result, it is possible that the expander 604 and the condenser 605 exhibit maximum performance. When the pressure Pevp and the temperature Tevp of the vapor are out of the predetermined relationship, by changing the ratio of expansion of the expander 604, the pressure Pexp2 and the temperature Texp2 of the vapor discharged from the expander 604 are matched to optimum values.
As illustrated in FIG. 15, Japanese Unexamined Patent Application Publication No. 2001-165513 discloses a refrigeration air conditioner 901 having a compressor 902, a radiator 916, an expander 903, and an evaporator 917. The refrigeration air conditioner 901 has an inlet pressure detector 941, an outlet pressure detector 942, an expansion ratio controller 943, and a calculator 944. The inlet pressure detector 941 detects a pressure at an inlet of the expander 903, and the outlet pressure detector 942 detects a pressure at an outlet of the expander 903. As the inlet pressure detector 941 and the outlet pressure detector 942, pressure sensors are used. Based on detection signals of the inlet pressure detector 941 and the outlet pressure detector 942, the calculator 944 calculates a target ratio of expansion. The expansion ratio controller 943 controls the expander 903 to expand a refrigerant 905 at the target ratio of expansion. In such a manner, the pressure after expansion of the refrigerant 905 introduced to the expander 903 is made equivalent to the pressure at the outlet of the expander 903. In Japanese Unexamined Patent Application Publication No. 2001-165513, there is a description that a temperature sensor may be provided at an outlet of the expander 903 to detect the temperature of the refrigerant 905, thereby obtaining the pressure at the outlet of the expander 903 based on the detected value.